The raw material for porcelain is a stone called pottery stone. Unlike the so-called "earthenware" pottery clay, pottery stone is white, hard, and non-absorbent. The pottery stone is crushed into small pieces to remove impurities such as iron, and then the clay for porcelain production (porcelain clay) is made.
Since the discovery of pottery stones at Mount Izumi in Arita Town in 1616, most of that one mountain has been mined to the point of disappearing, and the sight of the magnet field is one of 400 years of magnificent history.
Since the Taisho era (1912-1926), ceramic stones from Amakusa, Kumamoto Prefecture, have been used to produce 99% of Arita-yaki porcelain. It is said that only Senzan Pottery Stone and Amakusa Pottery Stone can be used to make porcelain without blending other clay or raw materials, and they are regarded as valuable and high-quality magnets that are unparalleled in the world.